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Introduction: Elafin is a serine protease inhibitor that is differentially expressed at the transcriptional level in human normal mammary epithelial cells and carcinomas with high levels in normal cells and absent or low levels in most breast carcinoma cells. We sought to evaluate the effect of overexpressing elafin in breast carcinoma cells on cell growth and survival. Methods: To overexpress the elafin gene in human breast carcinoma cells in vitro we constructed a type V recombinant adenovirus expressing the elafin transgene under control of the CMV promoter (Ad-elafin). We treated human breast cancer cells (MDA-MB-468 and Her-18) and immortalized breast epithelial cells (76NE6) with Ad-elafin at a multiplicity of infection (MOI) of 2000 and 2500 or an adenoviral vector expressing the luciferase reporter gene (Ad-Luc) as a control. . Cell viability was determined by MTT assay and apoptosis with fluorescence-activated cell sorting analysis (FACS) 72 hours after infection. We evaluated the effects of Ad-elafin on the expression of other genes by western blot. Results: Elafin was markedly overexpressed in each of the cell lines treated with Ad-elafin as assessed by western blot analysis. The breast cancer cells treated with Ad-elafin had significant growth inhibition as compared with controls. The breast epithelial cells did not demonstrate any growth inhibition with Ad-elafin treatment. There was an increase in subdiploid cell populations in the breast cancer cells treated with Ad-elafin but not the breast epithelial cells as measured by FACS analysis. Conclusions: These findings establish that elafin can inhibit growth and induce apoptosis differentially in breast carcinoma cell lines but not in normal breast epithelial cells. Elafin may be a useful therapeutic gene in the treatment of breast cancer.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]